Freewheel clutch and a method of transmitting power using a freewheel clutch

ABSTRACT

The present invention relates to a freewheel clutch and a method transmitting power from one shaft to another. The freewheel clutch which is shiftable in two rotational directions includes a drive shaft which can rotate in each of two directions, a catch element which is fixedly secured to the drive shaft, a driven shaft, an engagement mechanism arranged between the drive shaft and the driven shaft, a fixed member, a holding element frictionally engaging the fixed member, and a spring element biased to release the engagement mechanism from engagement with the driven shaft. The method of transmitting power utilizing the freewheel clutch includes rotating the drive shaft from a freewheel position in one of a clockwise and a counterclockwise direction, whereby the engagement mechanism is moved into an engagement position so as to rotate the driven shaft, and returning the drive shaft to the freewheel position.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation of U.S. applicationSer. No. 09/584,495 filed Jun. 1, 2000, the disclosure of which isexpressly incorporated by reference herein in its entirety. Further, thepresent application claims priority under 35 U.S.C. § 119 of GermanPatent Application No. 100 02 334.7, filed on Jan. 20, 2000, thedisclosure of which is expressly incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a freewheel clutch which isshiftable in two rotational directions. The invention also relates to amethod of transmitting power using a freewheel clutch which is shiftablein two rotational directions.

[0004] 2. Background of the Invention

[0005] Freewheel clutches or freewheels are in particular known inbicycle engineering. Austrian application AT-194253, for instance,discloses a freewheel and gear hub having a back-pedal brake forbicycles wherein ratchets operate without any noise. These ratchets arecontrolled by a friction sleeve which frictionally slides in the sleeveor in an annular member which is fixedly connected to the hub sleeve.The friction sleeve includes recesses for the ratchets, noses forlimiting the rotation, and frictional slide springs which rest on theannular member.

[0006] Furthermore, U.S. Pat. No. 2,181,665 shows a simple constructionof a freewheel acting in one direction. In this design, a spring-biasedratchet engages into recesses which are provided for the ratchet uponrotation of the hub in one rotational direction. However, it does notengage into the recesses upon rotation in the other rotationaldirection.

[0007] Furthermore, German application DE-3326420 shows a freewheelclutch which utilizes a driving clutch, half which includes two axiallyoffset eccentrics. However, the freewheel clutch is only intended fortransmitting a rotational movement from a drive element to a drivenelement in one direction of rotation. Moreover, an independent freerotational movement of the driven element is ensured in the samedirection of rotation when the speed thereof exceeds that of the driveelement.

[0008] Despite the great number of solutions offered in the field ofbicycles or similar devices, there continues to exist a need for afreewheel clutch which can be utilized, in particular, in pedal vehiclesfor children such as tricycles or Kettcars® which allow pedaling in boththe forward direction and the rearward direction from an initialinoperative position. Such a design should easily permit both a forwardmovement and a rearward movement, respectively, of the vehicle.Furthermore, there is also a need for a freewheeling design which actsin both directions and prevents the pedals from rotating, for instance,during travel in sloping terrain or while the vehicle is being pushed.Moreover, since a pedal drive acts in both directions, the freewheelmust also be operative in both directions for reasons of safety.Accordingly, such a design may make these devices safer by preventing auser from injuring their legs or feet on the pedals.

SUMMARY OF THE INVENTION

[0009] The present invention provides for a freewheel clutch of simpleconstruction and relatively low manufacturing costs which is shiftablein both rotational directions and includes a freewheel condition whichacts in both rotational directions.

[0010] According to the invention there is provided a freewheel clutchwhich is shiftable in both rotational directions, e.g., forwards orbackwards, clockwise or counterclockwise, etc., and which includes adouble-acting freewheel. The clutch includes a driver or catch which isfixedly and/or securely connected to a drive shaft and further includesan engagement mechanism which is arranged between the drive shaft and adriven shaft.

[0011] Additionally, the freewheel clutch utilizes a holding elementwhich engages the engagement mechanism and which is frictionally engagedwith or frictionally coupled to a fixed member which may be a vehicleframe. A spring element is utilized in the clutch such that in theinoperative state of the drive shaft, the engagement mechanism ismaintained out of engagement with the driven shaft. However, in thedriven state of the drive shaft, the engagement mechanism is placed intoengagement with the driven shaft via the catch.

[0012] Prior to engagement of the engagement mechanism with the drivenshaft, the engagement mechanism is engaged by the holding element in anon-rotating or stationary state, while the drive shaft and the catchare rotating due to pedaling. A frictional force, which is maintainedbetween the holding element and the fixed member, is designed to begreater than a resilient force which is exerted by the spring element.This design permits the engagement of the engagement mechanism with thedriven shaft when the drive shaft is rotated a predetermined amount.Furthermore, the clutch utilizes an engagement force is created betweenthe engagement mechanism and the driven shaft, which is greater than thefrictional force between holding element and fixed member. Accordingly,as a result of this design, a power transmission from the drive shaft tothe driven shaft via the catch and the engagement mechanism is therebymade possible.

[0013] Thus, according to the invention, it is possible to drive thedrive shaft forwards or rearwards (i.e., clockwise or counterclockwise)by pedaling a pedal vehicle. Moreover, this design easily achieves aforwardly directed movement or a rearwardly directed movement of thevehicle, depending on the respective drive direction of the drive shaftand/or pedals. Thus the freewheel clutch according to the invention canbe shifted into both rotational directions based upon movement of thepedals in the corresponding directions.

[0014] Furthermore, the invention provides a double-acting freewheelwhich makes it possible to move the pedal vehicle forwards or rearwardswithout pedaling. Accordingly, this design allows the pedals to remainstationary (e.g., not caused to be rotated) when the vehicle is pushedin either direction. Thus, when the vehicle is pushed in a forwarddirection, this movement will not cause forward corresponding movementof the pedals in the forward direction and vise versa. It is thus inparticular possible to push pedal vehicles with children thereonforwards or rearwards without producing any rotation of the pedals. As aresult, the risk of injury to the child's feet or legs is therebyreduced.

[0015] Preferably, the engagement mechanism which is located between thedrive shaft and the driven shaft is designed such that it permits apositive lock or positive engagement between a driving part and a drivenpart. This positive engagement design ensures a reliable connectionbetween the driving and the driven part. However, the invention alsocontemplates the use of frictional engagement by the engagementmechanism between the driving part and the driven part. Such a designallows for an even simpler construction of the freewheel clutch. Ofcourse, in each of these embodiments, the frictional force between theengagement mechanism and the driven shaft must be greater than thefrictional force between the holding element and the fixed member.

[0016] Preferably, the driven shaft is designed as an internally splinedhollow shaft. This allows for a compact freewheel clutch which is savesspace, in particular, in the axial direction.

[0017] In order to provide for a simple construction of the freewheelclutch, the spring element is preferably designed as a spring washer orring. The ring or washer may have an entirely annular shape or may bedesigned as a split ring or split washer so as to permit easy mountingand/or assembly/disassembly.

[0018] Advantageously, the engagement mechanism may be designed as alocking spline having external teeth or toothing. This design permits areliable positive teeth to teeth engagement so as to connect or couplethe drive shaft to the driven shaft.

[0019] In order to obtain a redundant engagement between the drive shaftand the driven shaft, the engagement mechanism may include two locks orengagement elements in which each engagement element utilizes anexternal spline, teeth or toothing.

[0020] Additionally, it is preferred that the catch is designed as asemi-annular element having two lateral wing sections. Utilizing thisdesign, the semi-annular element part of the catch can easily beconnected to the drive shaft, e.g. by conventional attachment techniquessuch as welding, bonding, fasteners, etc., or any combination thereof.

[0021] Moreover, in order to help reduce the risk of injury, a certainamount of motional or rotational play should exist in the drive shaftprior to the drive shaft being placed into engagement with the drivenshaft. The amount of play can of course be varied for the particularpurpose. However, it is preferred that this play be a total ofapproximately 30°. Accordingly, this design allows the pedals also havea motional or rotational play of approximately ±15° in either directionand around an axis running through the drive shaft. Again, this allowsfor a total motional or rotational play of the pedals of approximately30°. Stated another way, starting from a central or initial position,the pedals can be moved or rotated forwards by approximately 15° andrearwards by approximately 15° without the drive shaft causingcorresponding movement or rotation of the driven shaft.

[0022] In order to limit the movement of the catch in axial direction,at least one of the engagement elements of the engagement mechanismadvantageously includes inwardly projecting noses. Preferably, theholding element which cooperates with the engagement mechanism isdesigned as an annular or ring-like fork which has at least oneengagement or projection arm. Moreover, a fiber friction disk orfriction washer is arranged as a friction-producing element between theannular fork and the fixed member. This design permits a particularlyaxially compact construction. Moreover, the fiber friction washer isdesigned such that it can easily be replaced in case of wear.

[0023] The invention therefore provides for a freewheel clutch which isshiftable in two rotational directions, the clutch including a driveshaft which can rotate in each of two directions, a catch element whichis fixedly secured to the drive shaft, a driven shaft, an engagementmechanism arranged between the drive shaft and the driven shaft, a fixedmember, a holding element frictionally engaging the fixed member, and aspring element biased to release the engagement mechanism fromengagement with the driven shaft. The clutch may be a double-actingfreewheel clutch. The force of engagement between the engagementmechanism and the driven shaft may be greater than a frictional forceproduced by the frictional engagement between the fixed member and theholding element. The frictional force produced by the frictionalengagement between the fixed member and the holding element may begreater than a resilient force which prevents the engagement mechanismfrom engaging the driven shaft. The spring element may bias theengagement mechanism towards an axis of the drive shaft. The engagementmechanism may comprise at least two engagement elements. The springelement may bias the at least two engagement elements towards an axis ofthe drive shaft. The engagement mechanism may comprise a frictionengaging surface for frictionally engaging the driven shaft. Thefriction engaging surface may comprise at least one tooth. The frictionengaging surface may comprise a plurality of teeth. The driven shaft maycomprise a friction engaging surface having at least one tooth. The atleast one tooth of the driven shaft may be adapted to engage the atleast one tooth of the engagement mechanism. Rotation of the drive shaftmay cause corresponding rotation of the driven shaft when the at leastone tooth of the engagement mechanism engages the at least one tooth ofthe driven shaft.

[0024] The driven shaft may comprise a hollow shaft having a pluralityof an internal spline and a plurality of internal teeth. The springelement may comprise one of a spring washer and spring ring. The springelement may comprise one of a split spring washer and split spring ring.The engagement mechanism may comprise one of an external spline and aplurality of external teeth for engaging the driven shaft. Theengagement mechanism may comprise at least two engagement elements, eachof the at least two engagement elements having one of an external splineand a plurality of external teeth for engaging the driven shaft. Thecatch element may comprise a semi-annular section having two lateralwing sections projecting therefrom. The semi-annular section may befixedly secured to an exterior surface of the drive shaft. Thesemi-annular section may be fixedly secured to an exterior surface ofthe drive shaft by one of welding and boding.

[0025] The drive shaft may be adapted to rotate approximately 15° in aclockwise direction before the engagement mechanism engages the drivenshaft. The drive shaft may be adapted to rotate approximately 15° in acounterclockwise direction before the engagement mechanism engages thedriven shaft. The drive shaft may be adapted to rotate approximately 15°in each of a clockwise and a counterclockwise direction before theengagement mechanism engages the driven shaft. The engagement mechanismmay comprise at least one engagement element, the at least oneengagement element including at least one projecting portion. The atleast one projecting portion may comprise a stop for preventing thecatch element from moving in the axial direction. The at least oneprojecting portion may comprise at least two projecting portions. Thefixed member may comprises a sleeve. The sleeve may comprise an annularshoulder which frictionally engages the holding element. The sleeve maycomprise an opening for receiving the drive shaft.

[0026] The holding element may comprise an annular fork. The annularfork may comprises a washer portion and at least one arm projecting fromthe washer section. The at least one arm may be adapted to engage atleast one slot in the engagement mechanism. The at least one arm maycomprise at least two arms, each of the at least two arms being adaptedto engage a corresponding slot in the engagement mechanism.

[0027] The clutch may further comprise a friction washer arrangedbetween the holding element and the fixed member. The friction washermay be arranged between the holding element and an annular shoulder ofthe fixed member. The friction washer may comprise one of a fiber washerand a fiber lined washer. The clutch may further comprise one of aspring washer and a corrugated washer arranged against the holdingmember. The clutch may further comprise a cover for enclosing theengagement mechanism. The clutch may further comprise a securing diskfor securing the cover to the fixed member. Rotation of the drive shaftin at least one direction may cause the engagement mechanism to engagethe driven shaft. The clutch may comprise a pedal vehicle clutch.

[0028] The invention also provides for a freewheel clutch which isshiftable in two rotational directions, the clutch including a firstshaft which can rotate in each of two directions, a second shaftcomprising a hollow space, an opening for receiving the first shaft, andan internal friction surface, an engagement mechanism arranged withinthe hollow shape, the engagement mechanism comprising an exteriorfriction surface, a catch element fixedly secured to the drive shaft, afixed member comprising an opening for receiving the first shaft and anannular shoulder, a holding element for frictionally engaging theannular shoulder of the fixed member, and a spring element for biasingthe engagement mechanism towards the first shaft so as to prevent theexternal friction surface of the engagement mechanism from engaging theinternal friction surface of the second shaft, wherein rotation of thefirst shaft in at least one direction causes a corresponding rotation ofthe second shaft.

[0029] The clutch may be a double-acting freewheel clutch. The force ofengagement between the engagement mechanism and the second shaft may begreater than a frictional force produced by the frictional engagementbetween the fixed member and the holding element. The frictional forceproduced by the frictional engagement between the fixed member and theholding element may be greater than a resilient force which prevents theengagement mechanism from engaging the second shaft. The engagementmechanism may comprise at least two engagement elements. The externalfriction surface may comprise at least one tooth. The at least one toothmay comprise a plurality of teeth. The internal friction surface maycomprise one of an internal spline and a plurality of teeth. The atleast one tooth of the engagement mechanism may be adapted to engage oneof the internal spline and the plurality of teeth. Rotation of the firstshaft may cause corresponding rotation of the second shaft when the atleast one tooth of the engagement mechanism engages one of the internalspline and the plurality of teeth of the second shaft.

[0030] The spring element may comprise one of a split spring washer anda split spring ring. The engagement mechanism may comprise at least twoengagement elements, each of the at least two engagement elementscomprising the external friction surface, the external friction surfacefurther comprising one of an external spline and a plurality of externalteeth for engaging a corresponding spline or teeth disposed on theinternal friction surface of the second shaft. The catch element maycomprise a semi-annular section having two lateral wing sectionsprojecting therefrom. The semi-annular section may be fixedly secured toan exterior surface of the first shaft by one of welding and boding. Thefirst shaft may be adapted to rotate approximately 15° in a clockwisedirection before the engagement mechanism engages the second shaft. Thefirst shaft may be adapted to rotate approximately 15° in acounterclockwise direction before the engagement mechanism engages thesecond shaft. The first shaft may be adapted to rotate approximately 15°in each of a clockwise and a counterclockwise direction before theengagement mechanism engages the second shaft. The engagement mechanismmay comprise at least one engagement element, the at least oneengagement element including at least one projecting portion. The atleast one projecting portion may comprise at least two projectingportions.

[0031] The holding element may comprise an annular fork, the annularfork comprising a washer portion and at least one arm projecting fromthe washer section. The at least one arm may be adapted to engage atleast one slot in the engagement mechanism. The at least one arm maycomprise at least two arms, each of the at least two arms being adaptedto engage a corresponding slot in the engagement mechanism.

[0032] The clutch may further comprise a friction washer arrangedbetween the holding element and the annular shoulder of the fixedmember. The friction washer may comprise one of a fiber washer and afiber lined washer. The clutch may further comprise one of a springwasher and a corrugated washer arranged against the holding member. Theclutch may further comprise a cover for enclosing the engagementmechanism. The clutch may further comprise a securing disk for securingthe cover to the fixed member. The clutch may further comprise afriction washer arranged between the holding element and the annularshoulder of the fixed member, the friction washer comprises one of afiber washer and a fiber lined washer, one of a spring washer and acorrugated washer arranged against the holding member, a cover forenclosing the engagement mechanism, and a securing disk for securing thecover to the fixed member, wherein the holding element comprises anannular fork, the annular fork comprising a washer portion and at leasttwo arms, each of the at least two arms being adapted to engage acorresponding slot in the engagement mechanism. The clutch may comprisesa pedal vehicle clutch.

[0033] The invention also provides for a method of transmitting powerfrom a drive shaft to a driver shaft utilizing a freewheel clutch whichis shiftable in two rotational directions wherein the drive shaft isrotatable in each of two directions, the clutch including a catchelement which is fixedly secured to the drive shaft, an engagementmechanism arranged between the drive shaft and the driven shaft, a fixedmember, a holding element frictionally engaging the fixed member, and aspring element biased to release the engagement mechanism fromengagement with the driven shaft, the method comprising rotating thedrive shaft from a freewheel position in one of a clockwise and acounterclockwise direction, whereby the engagement mechanism is movedinto an engagement position so as to rotate the driven shaft, andreturning the drive shaft to the freewheel position. The drive shaft maybe rotatable in each of the clockwise and counterclockwise direction.The driven shaft may be freely rotating in one of the clockwise and thecounterclockwise direction prior to the rotating of the drive shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is further described in the detaileddescription which follows, in reference to the noted plurality ofdrawings by way of non-limiting examples of exemplary embodiments of thepresent invention, in which like reference numerals represent similarparts throughout the several views of the drawings, and wherein:

[0035]FIG. 1 is a perspective exploded view of a freewheel clutch with adouble-acting freewheel according to a preferred embodiment of thepresent invention;

[0036]FIG. 2 is a sectional view of the freewheel clutch shown in FIG.1, in the closed state of the freewheel, e.g., clockwise rotationalengagement of the engagement mechanism such that the drive shaft candrive the driven shaft to clockwise rotation;

[0037]FIG. 3 is a sectional view corresponding to FIG. 2, which showsthe freewheel clutch illustrated in FIG. 1 in the opened state of thefreewheel, e.g., initial non-rotated state; and

[0038]FIG. 4 is a partial sectional side view of the assembled freewheelclutch shown in FIGS. 1 to 3.

DESCRIPTION OF THE INVENTION

[0039] The particulars shown herein are by way of example and forpurposes of illustrative discussion of the embodiments of the presentinvention only and are presented in the cause of providing what isbelieved to be the most useful and readily understood description of theprinciples and conceptual aspects of the present invention. In thisregard, no attempt is made to show structural details of the presentinvention in more detail than is necessary for the fundamentalunderstanding of the present invention, the description taken with thedrawings making apparent to those skilled in the art how the severalforms of the present invention may be embodied in practice.

[0040] FIGS. 1 to 4 show a preferred embodiment of a freewheel clutchaccording to the invention utilizing a double-acting freewheel (i.e.,one acting in both clockwise and counterclockwise rotationaldirections). The freewheel clutch 1 permits the transmission of power inboth rotational directions, i.e., forwards and rearwards or clockwiseand counterclockwise. Freewheel clutch 1 is particularly suited for usein, e.g., tricycles and Kettcars® or other devices where it isadvantages to utilize freewheeling as well as forward and rearwardshifting.

[0041] As is particularly shown in FIG. 1, freewheel clutch 1 utilizes adrive shaft 2 and a driven shaft 4. Drive shaft 2 may be coupled to orcommunicate with a tread or crank with pedals (not shown). Moreover,drive shaft 2 may be rotated by a force exerted on such pedals. Driveshaft 2 is also designed to be driven in both rotational directions(i.e., clockwise and counterclockwise) so as to permit a forwardmovement and rearward movement, respectively, of the vehicle, e.g., apedal operated vehicle.

[0042] Freewheel clutch 1 also includes a driver or catch element ormechanism 3 which is fixedly and/or securely connected to drive shaft 2.Catch element 3 preferably includes a semi-annular section having twolateral wing sections projecting therefrom. Each wing section 23 alsohas a recess or slot 13 which cooperates with split ring 8 as will bemore clearly described further on. The connection between catch 3 andshaft 2 is preferably by way of welding or bonding, but otherconventional attachment techniques may also be employed. It is preferredthat shaft 2 and catch 3 be made of a metal, e.g., steel. However, othermaterials such as plastics and/or composites may also be utilizedprovided they contain sufficient strength to perform their functionreliably.

[0043] Furthermore, clutch 1 utilizes an engagement mechanism which mayhave two engagement elements or locking elements 5, 6 and which arearranged between drive shaft 2 and driven shaft 4. Engagement elements5, 6 are preferably designed as locking elements such that each has anexternal spline or toothing 20. Again, the preferred material for theseelements 5, 6 is a metal such as steel, but other materials may also beutilized. Alternatively, teeth 20 may be replaced with a frictionsurface or lining such as one found on some conventional centrifugalclutches. In this regard, this surface or lining may be similar to thefiber material utilized in fiber washer 10 which will be describedfurther on. Nevertheless, teeth 20 are preferred over a frictionallining or surface because of their long life and reliability.

[0044] Furthermore, freewheel clutch 1 according to the invention alsoutilizes a split ring or spring washer 8 which acts as a spring elementto bias locking elements 5 and 6 towards one another. Moreover, springelement 8 is received in recesses or grooves 14 which are respectivelyformed on each of locking elements 5 and 6. As shown in FIG. 1, aring-like fork 7 is utilized which includes two projecting arms 17. Eachprojecting arm 17 is designed to project into recesses or slots 15, 16formed on locking elements 5 and 6, respectively (see, in particular,FIG. 4).

[0045] As shown in FIG. 1, locking elements 5, 6 are preferably notsymmetrically formed. Thus, in contrast to locking element 5, lockingelement 6 can additionally include two projecting noses 19, whichproject towards locking element 5.

[0046] Furthermore, freewheel clutch 1 also includes a sleeve 9 whichmay be a fixed member, and a fiber disk or washer 10. Fiber washer 10 ispreferably a compression friction washer. Moreover, washer 10 isarranged between sleeve 9, more particularly annular shoulder 22 ofsleeve 9, and fork 7. Sleeve 9 may further be fixedly connected to anon-rotatable member such as the frame of the pedal vehicle (not shown).

[0047] Freewheel clutch 1 according to the invention additionallyincludes a corrugated washer 11 or similar type spring and/orcompression washer, a cover 12, and a securing disk 18 or similar typedevice which secures and/or helps retain the aforementioned individualmembers on drive shaft 2 in such a manner that the members cannot bedisplaced axially.

[0048] The operation of the freewheel clutch according to the inventionmay be described as follows. As is especially shown in FIGS. 2 and 3,catch 3 is arranged between locking elements 5 and 6. Locking elements5, 6 are in turn biased by spring element 8 to a predetermined extentand held around catch 3 and drive shaft 2, respectively, such thatlocking elements 5 and 6 are in contact with catch 3. Accordingly, catch3, and more particularly wing sections 23, include recesses or slots 13.Moreover, slots 13 are arranged at a particular position on catch 3, forthe purpose of receiving annular spring 8. Additionally, theabove-explained structures are preferably arranged in the axialdirection of the rotational axis A inside a portion of driven shaft 4.For this purpose, driven shaft 4 is designed as a hollow shaft (see forexample FIG. 4). As further shown in FIG. 4, the two arms 17 of fork 7are designed to axially grip or extend beyond fiber washer 10 andannular shoulder 22 of sleeve 9, into recesses or slots 15 and 16, whichare formed on each of locking elements 5 and 6 respectfully. Moreover,fork 7 is designed to be held or retained in an axial position orlocation by securing disk 18 via corrugated washer 11 and cover 12 (seeFIG. 4).

[0049] In FIG. 3, freewheel clutch 1 is illustrated in a state where thefreewheel is opened, i.e., initial non-rotated position. This means thatno force is exerted on the pedals such that the pedal vehicle can bepushed in both directions of travel, i.e. forwards and rearwards withoutcausing the pedals to be rotated as a result. When a force is thenexerted on the pedals, the force will be transmitted via drive shaft 2to catch 3 since catch 3 is fixed to shaft 2. Accordingly, this rotationforce causes catch 3 to begin to rotate at the same time as drive shaft2. However, since locking elements 5, 6 are directly positioned on catch3, the rotational force is immediately transmitted to locking elements5, 6 such that locking elements 5, 6 are caused to displace outwards andaway from the axis of shaft 2. Locking elements 5, 6, however, arenevertheless prevented from rotating yet because they are held by arms17 of fork 7. This is because fork 7 is prevented from rotating and thusheld stationary by reason of the friction which exists between fork 7,and more particularly annular shoulder 22 or fork 7, fiber washer 10,and fixed sleeve 9, respectively. As a result of this frictionalretention, locking elements 5, 6 are caused to radially moved ordisplace outwards guided by recesses 15 engaging arms 17 and against theresilient force of annular spring 8. The resilient force for holdinglocking elements 5, 6 together is accordingly designed to be smaller orless than the frictional force which is exerted between fork 7 and fiberwasher 10. The reason for this is because, otherwise, locking elements5, 6 could not be moved radially outwards. Moreover, as a result of thisdesign, engagement elements or locking elements 5, 6, with theirexternal toothing 20, are positively locked or positively engage withinternal toothing 21 of driven hollow shaft 4.

[0050] The force generated by the positive locking or engagement isdesigned to be greater than the frictional force produced by fiberwasher 10 on fork 7. As a result, this allows fork 7 to also begin torotate together with engagement elements 5, 6 and the drive shaft 2 andthe driven shaft 4, respectively, against the frictional resistance onfiber washer 10. Moreover, this design permits a positive powertransmission of the force exerted on the pedals to be transmitted to thedriven shaft 4. Such an engaged position of freewheel clutch 1 is shownin FIG. 2. Hence, in such an engaged position, the pedal vehicle can bemoved forwards or rearwards by way of pedaling. Note that FIG. 2 showsengagement on one (forward or clockwise) of the two positions.

[0051] When a frictional connection (e.g., frictional engagement betweenteeth 20 and teeth 21) is provided between hollow shaft 4 and engagementelements 5, 6, the frictional force created between hollow shaft 4 andengagement elements 5, 6 must be greater than the frictional forcebetween fork 7 and fiber washer 10, in order to obtain a functioningfreewheel clutch.

[0052] As is apparent from FIG. 2, catch 3 is in engagement via its twowing sections 23, with a respective one of locking elements 5, 6, e.g.,at the upper side and bottom side, respectively. As is clearly seen incomparison to FIG. 3, catch 3 has here been rotated (clockwise) out ofan initial position (FIG. 3) along axis A-A by approximately 15° toachieve a full engagement between engagement elements 5, 6 and drivenshaft 4. However, it should be noted that if the pedals were to berotated in the other direction (counterclockwise), catch 3 would berotated out of the initial position A-A by 15° into the oppositedirection (not shown). This would again bring engagement elements 5, 6into engagement with internal toothing 21 of driven shaft 4 (not shown).

[0053] Accordingly, there is an overall motional or rotational play ofapproximately less than 30° where no power is transmitted from driveshaft 2 to driven shaft 4 such that the freewheel is opened (i.e.,non-engaged) in both directions of travel.

[0054] Freewheel clutch 1 according to the invention thereby ensuresthat, when little or no force is exerted on the pedals, a freewheelexists in either a forwardly oriented direction and a rearwardlyoriented direction, such that the pedal vehicle can be pushed forwardsor rearwards without corresponding movement of the pedals. When a forceis then exerted on the pedals in a specific direction, engagementbetween engagement elements 5, 6 and driven shaft 4 can commence after apredetermined amount of rotational play (e.g. 15° in either directionfor a total of approximately 30°). As a result, the force of the pedalscan then be transmitted to driven shaft 4.

[0055] It should be noted here that the rotational play can especiallybe varied by adjusting the distance between engagement elements 5, 6 anddriven shaft 4. Moreover, the invention is not limited to rotationalplays of 15° and/or 30°. However, these plays are believed to be idealfor pedal type devices are therefore recommended.

[0056] Freewheeling clutch 1 operates equally well in either direction.Thus, when a force is exerted on the pedals in another direction, e.g.counterclockwise, engagement elements 5, 6 also engage into driven shaft4 which is then rotated in the rearward direction (not shown). Thus thepedal vehicle can be moved both in the forward and rearward direction byway of pedaling.

[0057] Thus, the invention provides for a freewheel clutch 1 which isshiftable in both rotational directions (forwards and/or clockwise andrearward and/or counterclockwise) and includes a double-actingfreewheel. Freewheel clutch 1 utilizes a catch 3 which is fixedly andsecurely connected to a drive shaft 2, and an engagement mechanismhaving engagement elements 5, 6 arranged between drive shaft 2 and adriven shaft 4. Furthermore, a holding element 7 is utilized which iscoupled to or engaged with a fixed member 9 via frictional resistance.Moreover, holding element 7 cooperates with engagement elements 5, 6,via recesses. Additionally, engagement elements 5, 6 are biased towardsone another and shaft 2 via a spring element 8. Spring element 8 isdesigned such that when shaft 2 is in the non-rotating state, engagementelements 5, 6 are out of engagement with driven shaft 4. Moreover, whenshaft 2 is in the driven, i.e. rotating, state, spring element 8 issufficiently weak to allow engagement elements 5, 6 to be in engagementwith driven shaft 4 via the catch 3.

[0058] It is preferred that most of the parts described herein be madeof a material such as steel. Thus it is preferred that shaft 2, shaft 4,elements 5 and 6, catch 3, washers 7, 8 and 11, sleeve 9 and disk 18 allbe made of a metal such as steel since it is relatively inexpensive,strong, and relatively easy to work with. However, cover 12 may be madefrom plastic or composite as well as metal. Moreover, fiber washer 10may be a combination of a metal washer utilizing a fiber lining or itmay be simply made of fiber or similar composite material. Accordingly,the invention is not limited to these so listed materials.Considerations of weight, cost, wear life, and reliability may requirethat lighter materials be utilized such as aluminum, plastics, andcomposites and/or a combination thereof.

[0059] It is noted that the foregoing examples have been provided merelyfor the purpose of explanation and are in no way to be construed aslimiting of the present invention. While the present invention has beendescribed with reference to an exemplary embodiment, it is understoodthat the words which have been used herein are words of description andillustration, rather than words of limitation. Changes may be made,within the purview of the appended claims, as presently stated and asamended, without departing from the scope and spirit of the presentinvention in its aspects. Although the present invention has beendescribed herein with reference to particular means, materials andembodiments, the present invention is not intended to be limited to theparticulars disclosed herein; rather, the present invention extends toall functionally equivalent structures, methods and uses, such as arewithin the scope of the appended claims.

What is claimed is:
 1. A freewheel clutch which is shiftable in tworotational directions, the clutch comprising; a drive shaft which canrotate in each of two directions; a catch element which is fixedlysecured to the drive shaft; a driven shaft; an engagement mechanismarranged between the drive shaft and the driven shaft; a fixed member; aholding element frictionally engaging the fixed member; and a springelement biased to release the engagement mechanism from engagement withthe driven shaft.
 2. The clutch of claim 1, wherein the clutch is adouble-acting freewheel clutch.
 3. The clutch of claim 1, wherein aforce of engagement between the engagement mechanism and the drivenshaft is greater than a frictional force produced by the frictionalengagement between the fixed member and the holding element.
 4. Theclutch of claim 3, wherein the frictional force produced by thefrictional engagement between the fixed member and the holding elementis greater than a resilient force which prevents the engagementmechanism from engaging the driven shaft.
 5. The clutch of claim 1,wherein the spring element biases the engagement mechanism towards anaxis of the drive shaft.
 6. The clutch of claim 1, wherein theengagement mechanism comprises at least two engagement elements.
 7. Theclutch of claim 6, wherein the spring element biases the at least twoengagement elements towards an axis of the drive shaft.
 8. The clutch ofclaim 1, wherein the engagement mechanism comprises a friction engagingsurface for frictionally engaging the driven shaft.
 9. The clutch ofclaim 8, wherein the friction engaging surface comprises at least onetooth.
 10. The clutch of claim 9, wherein the friction engaging surfacecomprises a plurality of teeth.
 11. The clutch of claim 9, wherein thedriven shaft comprises a friction engaging surface having at least onetooth.
 12. The clutch of claim 11, wherein the at least one tooth of thedriven shaft is adapted to engage the at least one tooth of theengagement mechanism.
 13. The clutch of claim 12, wherein rotation ofthe drive shaft causes corresponding rotation of the driven shaft whenthe at least one tooth of the engagement mechanism engages the at leastone tooth of the driven shaft.
 14. The clutch of claim 1, wherein thedriven shaft comprises a hollow shaft having a plurality of an internalspline and a plurality of internal teeth.
 15. The clutch of claim 1,wherein the spring element comprises one of a spring washer and springring.
 16. The clutch of claim 15, wherein the spring element comprisesone of a split spring washer and split spring ring.
 17. The clutch ofclaim 1, wherein the engagement mechanism comprises one of an externalspline and a plurality of external teeth for engaging the driven shaft.18. A freewheel clutch which is shiftable in two rotational directions,the clutch comprising; a first shaft which can rotate in two directions;a second shaft comprising an opening for receiving the first shaft, andan internal friction surface; an engagement mechanism comprising anexterior friction surface; a catch element secured to the drive shaft; afixed member comprising an opening for receiving the first shaft and anannular shoulder; a holding element for frictionally engaging theannular shoulder of the fixed member; and a spring element forpreventing biasing the engagement mechanism towards the first shaft,wherein rotation of the first shaft in at least one direction causes acorresponding rotation of the second shaft.
 19. A method of transmittingpower from a drive shaft to a driver shaft utilizing a freewheel clutchwhich is shiftable in two rotational directions wherein the drive shaftis rotatable in each of two directions, the clutch including a catchelement which is fixedly secured to the drive shaft, an engagementmechanism arranged between the drive shaft and the driven shaft, a fixedmember, a holding element frictionally engaging the fixed member, and aspring element biased to release the engagement mechanism fromengagement with the driven shaft, the method comprising: rotating thedrive shaft from a freewheel position in one of a clockwise and acounterclockwise direction, whereby the engagement mechanism is movedinto an engagement position so as to rotate the driven shaft; andreturning the drive shaft to the freewheel position.
 20. The method ofclaim 19, wherein the drive shaft is rotatable in each of the clockwiseand counterclockwise direction and wherein the driven shaft is freelyrotatable in one of the clockwise and the counterclockwise directionprior to the rotating of the drive shaft.